PROJECT SUMMARY Alcohol and other drug (AOD) misuse is a major health and safety problem that most commonly begins during adolescence. AOD use during adolescence can lead to many short- and long-term negative consequences including altered academic and employment trajectories, incarceration, susceptibility to future drug problems, cortical damage, and impaired adult cognitive functioning. Relapse prevention is currently the standard treatment for adolescent AOD users who have chosen abstinence. Reminders of one's commitment to abstinence, such as alarm clocks and calendars, can serve as support mechanisms for relapse prevention. With the advent of newer technology (e.g., smart-phones), the potential arises to update these reminder mechanisms. Because adolescents are often first adopters of new technology, new reminder methods may be particularly effective with them. Research on applying technology to substance abuse treatment has focused on the effect of text-message interventions for individuals not seeking treatment. We are aware of no studies investigating the effect of texting as a support mechanism for substance abuse relapse prevention. The current study proposes to apply text messages as a supportive reminder and adjunct to substance abuse counseling with adolescents. Three groups (N = 150) will be compared: a group of youth who self-select their messages (N = 50), a yoked group who are assigned messages (N = 50), and a treatment as usual control condition (N = 50). Messages will be sent in a random order and at randomized time intervals for four weeks. Data collected through this study will examine the impact of text message content on relapse rates. Data also will be gathered to measure the impact of the messages on self-efficacy and receptivity of youth to these messages. These data will provide preliminary findings necessary for continued research on the utility of technology in clinical practice and provide training to a promising young researcher.